WIND SPEED PROBABILITY DISTRIBUTION WITHIN AND ABOVE A STREET CANYON IN AKURE, NIGERIA

Abstract

Wind speed probability distribution within and above a street canyon in Akure has been investigated in other to determine the frequency and distribution of flow of wind within and above the urban street canyons in Akure South-west Nigeria. The data used for this study were obtained between August 2013 – November, 2013 in the street canyon bordered by the Akure central mosque to the north and the Oja-Oba (Oba’s Ultra-Modern Market) to the south on Oba Adesida road, Akure. Wind speed and direction were simultaneously monitored three levels ( in-street, 3m and roof level, 10m and 12m) using RM Young wind sentry connected to a Campbell Scientific CR200 data logger powered by a 12V rechargeable battery and solar panel. Wind speed and direction were logged every minute. Data analysis was achieved using exploratory data analysis with Microsoft Excel and R statistical software. The data were fitted to the Generalized Extreme Value, Log-Normal and Weibull probability distributions. Evidence of flow channelling (2500- 3000) and recirculation (1400-1900) were identified within the canyon for roof level flows in the sectors (2000-2500) and(2500-2700) The plotting positions and probability distributions show that Weibull’s plotting position gave minimal errors with the root mean square errors for Generalised Extreme Value. The results testifyed that the small changes in roof level wind direction have profound influences on the behaviour of in-street flow patterns.